The invention relates to a twin-wheel castor.
A variety of twin-wheet castor structures exist, but these in general fall short of optimum requirements in respect for example of utilisation of materials and simplicity of assembly.
It is accordingly an object of the invention to provide a castor comprising a small number of parts, which can be readily assembled together.
It is also an object of the invention to provide a castor which makes economical use of conveniently available materials.
It is a further object of the invention to provide a castor in which utilisation of movable bearing parts is minimized.
It is an additional object of the present invention to provide a castor including ball bearing means in which the ball bearing races are integrally formed portions of the castor.
The present invention provides a castor comprising a body journalling a pair of wheels for rotation about a common axis and having means whereby the castors can be mounted on an article of furniture or the like for swivelling about a substantially vertical axis, the wheels being journalled on the body by a single common ball bearing.
Conveniently, the body provides an apertured wheel mounting portion between the wheels, the edges of the aperture being shaped to constitute an outer race for the ball bearing. Each wheel has an inwardly projecting hub portion, the two hub portions being secured together by fastener means so as to permit differential wheel rotation and being shaped so that they together form the inner race of the ball bearing.
A twin-wheel castor embodying the invention can comprise a body and wheels of plastics material, only a swivel pin for mounting the body on an article of furniture or the like, the balls of the ball bearing and retaining means holding the wheels in engagement with the balls of the bearing being of metal.
Thus a twin-wheel castor is provided in accordance with the invention which is of simple construction, and formed mainly of readily mouldable plastics components, metal components being employed only where necessary.